---
title: Propel API versioning policy
description: Versioning, compatibility and deprecation policy for the Propel CRM API.
canonical: https://www.propelai.co.uk/api-versioning.md
last-updated: 2026-08-21
---

# Propel API versioning policy

The supported CRM REST surface is currently `/api/crm/v1`. The version is
part of the URL so an agent can see which contract it is calling before it
sends a request.

## Compatibility

- Additive fields, endpoints and optional query parameters are preferred.
- Existing fields keep their documented meaning within a major version.
- Write requests should use `Idempotency-Key` when a client may retry after a
  network failure.
- Every request remains subject to bearer authentication, rate limits and the
  account's approval boundaries.

## Deprecation

Propel does not currently have a deprecated CRM API operation. If an operation
needs to be retired, the change will be documented here and in the OpenAPI
description before removal. The notice will identify the affected operation,
replacement route, migration period and planned sunset date. During a live
deprecation, responses will also carry `Deprecation` and `Sunset` headers.

Read the [OpenAPI description](https://www.propelai.co.uk/openapi.json) and
[API directory](https://www.propelai.co.uk/api) for the current
operation contract.